Generally speaking, magnetic devices, such a transformer, inductance, and etc., are disposed in electronic equipment. To match the trend of reducing the thickness of the electronic equipment, the magnetic devices of the electronic equipment and the conductive winding structure applied in the magnetic devices have to be thinned, so as to decrease the whole volume of the electronic equipment.
Take transformer for example, the wires are wound on the bobbin to serve as the primary winding and the secondary winding of the transformer in the conventional technique. Since certain amount of space on the bobbin has to be preserved for winding the primary and seconding windings, the volume of the transformer cannot be reduced. A technique of forming the conductive winding structure with the cut copper sheet developed to replace the wire winding technique can decrease the thickness of the conductive winding structure; however, to produce a conductive winding structure with multiple windings, several single cut copper sheets have to be soldered together, or a whole copper sheet with specific shape has to be folded. In other words, the additional soldering or folding process has to be performed after cutting the copper sheet, which complicates the fabricating method. In addition, the thickness uniformity of the conductive winding structure is easily impacted owing to the soldering media or folding, and the structural damage and fold are easily created due to the folding process. The non-uniform thickness and the structural damage of the conductive winding structure will increase the power loss. Besides, when a thin copper sheet is folded, it may break easily. Hence the electrical property of the conductive winding structure and the efficiency and product yield of the transformer will be affected as well.
There is another technique of bending the flat cable with width larger than thickness by machine to form the conductive winding structure with multiple windings for lowering power loss; however, the width/thickness ratio of the flat cable used in this technique is usually smaller than 20. That is to say, when the thickness of the flat cable is reduced or the width/thickness ratio of the flat cable is increased, the conductive winding structure cannot be produced because the outer diameter and the inner diameter thereof may break and wrinkle respectively due to the insufficient malleability of the flat cable. In addition, a cable has only two terminals, and thus the conductive winding structure formed by bending a flat cable has only two conductive pins extended therefrom. Therefore, the application of the conductive winding structure with only two conductive pins will be limited. Though additional conductive pins can be soldered on the conductive winding structure to increase the number thereof, the processing procedure is complicated and time-consuming. It is to be understood that the conductive winding structure fabricated by the conventional techniques cannot satisfy the requirements for reducing the thickness and improving the electrical property thereof at the same time.
Accordingly, it is required to develop a conductive winding structure, a fabricating method thereof, and a magnetic device having the same to overcome the foregoing defects.